Embodiments of the inventive concept described herein relate to a radiotherapy apparatus that enhances a surface dose of a tumor that is a target object, by using a magnetic field, and more particularly to a radiotherapy apparatus that enhances a surface dose of a tumor by applying a magnetic field in a direction that is parallel to a radiation beam and thus concentrating scattering charged particles that are generated due to the heterogeneous density of human body tissues included within the beam locus of the radiation without diverging the charged particles in order to prevent the charged particles from scattering to outside of the tumor surface that is a treatment target, thereby improving a radiotherapy effect.
The radiotherapy apparatus is medical equipment that uses radiation in treatment of diseases, and is widely used to retard, stop, or even destruct growth of malignant tumors, such as cancers, by using ionizing radiation, including photon, electron or charged particle beam.
Meanwhile, because the charged particles that have scattered in a beam locus of the radiation diverge as their free flight distances increase in an interior (or a low density space) of an organ, such as a lung, an oral cavity, or an airway, there is ‘Build-up phenomenon’ in which absorbed radiation dose at a surface of a tumor is decreased.
Accordingly, because a surface of a tumor that is adjacent to a low density area gets lower radiation dose, a larger amount of radiation need to be irradiated to compensate lower radiation dose at the tumor surface, and consequently, normal tissues nearby the tumor get high dose of radiation.
In particular, the lung tumor requires a larger amount of radiation to be irradiated so that a dose that is necessary for the tumor destruction is delivered to the surface of the tumor because the tumor is surrounded by low density materials (normal lung tissues), and as a result, the treatment effect decreases due to the side effect of the radiation as the radiation dose delivered to the normal lung tissues increase.
Accordingly, if a method through which charged particles that are apt to diverge may be concentrated on a surface of a tumor is developed, an additional radiation dose for compensating for divergence of the charged particles from the tumor surface to surrounding normal tissues can be eliminated.
Accordingly, a radiotherapy apparatus that enhances a surface dose by concentrating the charged particles on a tumor by applying a magnetic field that is parallel to the direction of a beam of a radiation to a portion at which scattering charged particles diverge has been developed.